<AL, EL = never, RL = never>(
layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>,
options?: { readonly local?: boolean | undefined } | undefined
): <A, E, R>(
self: Stream<A, E, R>
) => Stream<A, E | EL, Exclude<R, AL> | RL>
<A, E, R, AL, EL = never, RL = never>(
self: Stream<A, E, R>,
layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>,
options?: { readonly local?: boolean | undefined } | undefined
): Stream<A, E | EL, Exclude<R, AL> | RL>Provides a layer or context to the stream, removing the corresponding
service requirements. Use options.local to build the layer every time; by
default, layers are shared between provide calls.
Example (Providing stream requirements)
import { Console, Context, Effect, Layer, Stream } from "effect"
class Env extends Context.Service<Env, { readonly name: string }>()("Env") {}
const layer = Layer.succeed(Env)({ name: "Ada" })
const stream = Stream.fromEffect(
Effect.gen(function*() {
const env = yield* Effect.service(Env)
return `Hello, ${env.name}`
})
)
const withEnv = stream.pipe(Stream.provide(layer))
const program = Stream.runCollect(withEnv).pipe(
Effect.flatMap((values) => Console.log(values))
)
Effect.runPromise(program)
// Output:
// ["Hello, Ada"]services
Source effect/Stream.ts:1003123 lines
export const const provide: {
<AL, EL = never, RL = never>(
layer:
| Layer.Layer<AL, EL, RL>
| Context.Context<AL>,
options?:
| { readonly local?: boolean | undefined }
| undefined
): <A, E, R>(
self: Stream<A, E, R>
) => Stream<A, E | EL, Exclude<R, AL> | RL>
<A, E, R, AL, EL = never, RL = never>(
self: Stream<A, E, R>,
layer:
| Layer.Layer<AL, EL, RL>
| Context.Context<AL>,
options?:
| { readonly local?: boolean | undefined }
| undefined
): Stream<A, E | EL, Exclude<R, AL> | RL>
}
Provides a layer or context to the stream, removing the corresponding
service requirements. Use options.local to build the layer every time; by
default, layers are shared between provide calls.
Example (Providing stream requirements)
import { Console, Context, Effect, Layer, Stream } from "effect"
class Env extends Context.Service<Env, { readonly name: string }>()("Env") {}
const layer = Layer.succeed(Env)({ name: "Ada" })
const stream = Stream.fromEffect(
Effect.gen(function*() {
const env = yield* Effect.service(Env)
return `Hello, ${env.name}`
})
)
const withEnv = stream.pipe(Stream.provide(layer))
const program = Stream.runCollect(withEnv).pipe(
Effect.flatMap((values) => Console.log(values))
)
Effect.runPromise(program)
// Output:
// ["Hello, Ada"]
provide: {
<function (type parameter) AL in <AL, EL = never, RL = never>(layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): <A, E, R>(self: Stream<A, E, R>) => Stream<A, E | EL, Exclude<R, AL> | RL>
function (type parameter) EL in <AL, EL = never, RL = never>(layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): <A, E, R>(self: Stream<A, E, R>) => Stream<A, E | EL, Exclude<R, AL> | RL>
function (type parameter) RL in <AL, EL = never, RL = never>(layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): <A, E, R>(self: Stream<A, E, R>) => Stream<A, E | EL, Exclude<R, AL> | RL>
layer: | Layer.Layer<AL, EL, RL>
| Context.Context<AL>
import LayerLayer.interface Layer<in ROut, out E = never, out RIn = never>A Layer describes how to build one or more services for dependency injection.
When to use
Use to model construction of application services for dependency injection,
especially when services have dependencies, can fail during construction, or
need scoped setup and release.
Details
A Layer<ROut, E, RIn> represents ROut as the services this layer
provides, E as the possible errors during layer construction, and RIn as
the services this layer requires as dependencies.
Layer<function (type parameter) AL in <AL, EL = never, RL = never>(layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): <A, E, R>(self: Stream<A, E, R>) => Stream<A, E | EL, Exclude<R, AL> | RL>
function (type parameter) EL in <AL, EL = never, RL = never>(layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): <A, E, R>(self: Stream<A, E, R>) => Stream<A, E | EL, Exclude<R, AL> | RL>
function (type parameter) RL in <AL, EL = never, RL = never>(layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): <A, E, R>(self: Stream<A, E, R>) => Stream<A, E | EL, Exclude<R, AL> | RL>
import ContextContext.interface Context<in Services>Immutable collection of service implementations used for dependency
injection in Effect programs.
Details
The type parameter tracks the service identifiers available in the context.
At runtime, services are stored by each key's string key.
Example (Creating a context with multiple services)
import { Context } from "effect"
// Create a context with multiple services
const Logger = Context.Service<{ log: (msg: string) => void }>("Logger")
const Database = Context.Service<{ query: (sql: string) => string }>(
"Database"
)
const context = Context.make(Logger, {
log: (msg: string) => console.log(msg)
})
.pipe(Context.add(Database, { query: (sql) => `Result: ${sql}` }))
Context<function (type parameter) AL in <AL, EL = never, RL = never>(layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): <A, E, R>(self: Stream<A, E, R>) => Stream<A, E | EL, Exclude<R, AL> | RL>
options: | {
readonly local?: boolean | undefined
}
| undefined
local?: boolean | undefinedlocal?: boolean | undefined
} | undefined
): <function (type parameter) A in <A, E, R>(self: Stream<A, E, R>): Stream<A, E | EL, Exclude<R, AL> | RL>A, function (type parameter) E in <A, E, R>(self: Stream<A, E, R>): Stream<A, E | EL, Exclude<R, AL> | RL>E, function (type parameter) R in <A, E, R>(self: Stream<A, E, R>): Stream<A, E | EL, Exclude<R, AL> | RL>R>(
self: Stream<A, E, R>(parameter) self: {
channel: Channel.Channel<Arr.NonEmptyReadonlyArray<A>, E, void, unknown, unknown, unknown, R>;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
}
interface Stream<out A, out E = never, out R = never>A Stream<A, E, R> describes a program that can emit many A values, fail
with E, and require R.
Details
Streams are pull-based with backpressure and emit chunks to amortize effect
evaluation. They support monadic composition and error handling similar to
Effect, adapted for multiple values.
Example (Creating and consuming streams)
import { Console, Effect, Stream } from "effect"
const program = Effect.gen(function*() {
yield* Stream.make(1, 2, 3).pipe(
Stream.map((n) => n * 2),
Stream.runForEach((n) => Console.log(n))
)
})
Effect.runPromise(program)
// Output:
// 2
// 4
// 6
Stream<function (type parameter) A in <A, E, R>(self: Stream<A, E, R>): Stream<A, E | EL, Exclude<R, AL> | RL>A, function (type parameter) E in <A, E, R>(self: Stream<A, E, R>): Stream<A, E | EL, Exclude<R, AL> | RL>E, function (type parameter) R in <A, E, R>(self: Stream<A, E, R>): Stream<A, E | EL, Exclude<R, AL> | RL>R>
) => interface Stream<out A, out E = never, out R = never>A Stream<A, E, R> describes a program that can emit many A values, fail
with E, and require R.
Details
Streams are pull-based with backpressure and emit chunks to amortize effect
evaluation. They support monadic composition and error handling similar to
Effect, adapted for multiple values.
Example (Creating and consuming streams)
import { Console, Effect, Stream } from "effect"
const program = Effect.gen(function*() {
yield* Stream.make(1, 2, 3).pipe(
Stream.map((n) => n * 2),
Stream.runForEach((n) => Console.log(n))
)
})
Effect.runPromise(program)
// Output:
// 2
// 4
// 6
Stream<function (type parameter) A in <A, E, R>(self: Stream<A, E, R>): Stream<A, E | EL, Exclude<R, AL> | RL>A, function (type parameter) E in <A, E, R>(self: Stream<A, E, R>): Stream<A, E | EL, Exclude<R, AL> | RL>E | function (type parameter) EL in <AL, EL = never, RL = never>(layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): <A, E, R>(self: Stream<A, E, R>) => Stream<A, E | EL, Exclude<R, AL> | RL>
type Exclude<T, U> = T extends U
? never
: T
Exclude from T those types that are assignable to U
Exclude<function (type parameter) R in <A, E, R>(self: Stream<A, E, R>): Stream<A, E | EL, Exclude<R, AL> | RL>R, function (type parameter) AL in <AL, EL = never, RL = never>(layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): <A, E, R>(self: Stream<A, E, R>) => Stream<A, E | EL, Exclude<R, AL> | RL>
function (type parameter) RL in <AL, EL = never, RL = never>(layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): <A, E, R>(self: Stream<A, E, R>) => Stream<A, E | EL, Exclude<R, AL> | RL>
function (type parameter) A in <A, E, R, AL, EL = never, RL = never>(self: Stream<A, E, R>, layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): Stream<A, E | EL, Exclude<R, AL> | RL>
function (type parameter) E in <A, E, R, AL, EL = never, RL = never>(self: Stream<A, E, R>, layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): Stream<A, E | EL, Exclude<R, AL> | RL>
function (type parameter) R in <A, E, R, AL, EL = never, RL = never>(self: Stream<A, E, R>, layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): Stream<A, E | EL, Exclude<R, AL> | RL>
function (type parameter) AL in <A, E, R, AL, EL = never, RL = never>(self: Stream<A, E, R>, layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): Stream<A, E | EL, Exclude<R, AL> | RL>
function (type parameter) EL in <A, E, R, AL, EL = never, RL = never>(self: Stream<A, E, R>, layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): Stream<A, E | EL, Exclude<R, AL> | RL>
function (type parameter) RL in <A, E, R, AL, EL = never, RL = never>(self: Stream<A, E, R>, layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): Stream<A, E | EL, Exclude<R, AL> | RL>
self: Stream<A, E, R>(parameter) self: {
channel: Channel.Channel<Arr.NonEmptyReadonlyArray<A>, E, void, unknown, unknown, unknown, R>;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
}
interface Stream<out A, out E = never, out R = never>A Stream<A, E, R> describes a program that can emit many A values, fail
with E, and require R.
Details
Streams are pull-based with backpressure and emit chunks to amortize effect
evaluation. They support monadic composition and error handling similar to
Effect, adapted for multiple values.
Example (Creating and consuming streams)
import { Console, Effect, Stream } from "effect"
const program = Effect.gen(function*() {
yield* Stream.make(1, 2, 3).pipe(
Stream.map((n) => n * 2),
Stream.runForEach((n) => Console.log(n))
)
})
Effect.runPromise(program)
// Output:
// 2
// 4
// 6
Stream<function (type parameter) A in <A, E, R, AL, EL = never, RL = never>(self: Stream<A, E, R>, layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): Stream<A, E | EL, Exclude<R, AL> | RL>
function (type parameter) E in <A, E, R, AL, EL = never, RL = never>(self: Stream<A, E, R>, layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): Stream<A, E | EL, Exclude<R, AL> | RL>
function (type parameter) R in <A, E, R, AL, EL = never, RL = never>(self: Stream<A, E, R>, layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): Stream<A, E | EL, Exclude<R, AL> | RL>
layer: | Layer.Layer<AL, EL, RL>
| Context.Context<AL>
import LayerLayer.interface Layer<in ROut, out E = never, out RIn = never>A Layer describes how to build one or more services for dependency injection.
When to use
Use to model construction of application services for dependency injection,
especially when services have dependencies, can fail during construction, or
need scoped setup and release.
Details
A Layer<ROut, E, RIn> represents ROut as the services this layer
provides, E as the possible errors during layer construction, and RIn as
the services this layer requires as dependencies.
Layer<function (type parameter) AL in <A, E, R, AL, EL = never, RL = never>(self: Stream<A, E, R>, layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): Stream<A, E | EL, Exclude<R, AL> | RL>
function (type parameter) EL in <A, E, R, AL, EL = never, RL = never>(self: Stream<A, E, R>, layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): Stream<A, E | EL, Exclude<R, AL> | RL>
function (type parameter) RL in <A, E, R, AL, EL = never, RL = never>(self: Stream<A, E, R>, layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): Stream<A, E | EL, Exclude<R, AL> | RL>
import ContextContext.interface Context<in Services>Immutable collection of service implementations used for dependency
injection in Effect programs.
Details
The type parameter tracks the service identifiers available in the context.
At runtime, services are stored by each key's string key.
Example (Creating a context with multiple services)
import { Context } from "effect"
// Create a context with multiple services
const Logger = Context.Service<{ log: (msg: string) => void }>("Logger")
const Database = Context.Service<{ query: (sql: string) => string }>(
"Database"
)
const context = Context.make(Logger, {
log: (msg: string) => console.log(msg)
})
.pipe(Context.add(Database, { query: (sql) => `Result: ${sql}` }))
Context<function (type parameter) AL in <A, E, R, AL, EL = never, RL = never>(self: Stream<A, E, R>, layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): Stream<A, E | EL, Exclude<R, AL> | RL>
options: | {
readonly local?: boolean | undefined
}
| undefined
local?: boolean | undefinedlocal?: boolean | undefined
} | undefined
): interface Stream<out A, out E = never, out R = never>A Stream<A, E, R> describes a program that can emit many A values, fail
with E, and require R.
Details
Streams are pull-based with backpressure and emit chunks to amortize effect
evaluation. They support monadic composition and error handling similar to
Effect, adapted for multiple values.
Example (Creating and consuming streams)
import { Console, Effect, Stream } from "effect"
const program = Effect.gen(function*() {
yield* Stream.make(1, 2, 3).pipe(
Stream.map((n) => n * 2),
Stream.runForEach((n) => Console.log(n))
)
})
Effect.runPromise(program)
// Output:
// 2
// 4
// 6
Stream<function (type parameter) A in <A, E, R, AL, EL = never, RL = never>(self: Stream<A, E, R>, layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): Stream<A, E | EL, Exclude<R, AL> | RL>
function (type parameter) E in <A, E, R, AL, EL = never, RL = never>(self: Stream<A, E, R>, layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): Stream<A, E | EL, Exclude<R, AL> | RL>
function (type parameter) EL in <A, E, R, AL, EL = never, RL = never>(self: Stream<A, E, R>, layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): Stream<A, E | EL, Exclude<R, AL> | RL>
type Exclude<T, U> = T extends U
? never
: T
Exclude from T those types that are assignable to U
Exclude<function (type parameter) R in <A, E, R, AL, EL = never, RL = never>(self: Stream<A, E, R>, layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): Stream<A, E | EL, Exclude<R, AL> | RL>
function (type parameter) AL in <A, E, R, AL, EL = never, RL = never>(self: Stream<A, E, R>, layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): Stream<A, E | EL, Exclude<R, AL> | RL>
function (type parameter) RL in <A, E, R, AL, EL = never, RL = never>(self: Stream<A, E, R>, layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): Stream<A, E | EL, Exclude<R, AL> | RL>
dual<(...args: Array<any>) => any, <A, E, R, AL, EL = never, RL = never>(self: Stream<A, E, R>, layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined) => Stream<A, E | EL, Exclude<R, AL> | RL>>(isDataFirst: (args: IArguments) => boolean, body: <A, E, R, AL, EL = never, RL = never>(self: Stream<A, E, R>, layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined) => Stream<A, E | EL, Exclude<R, AL> | RL>): ((...args: Array<any>) => any) & (<A, E, R, AL, EL = never, RL = never>(self: Stream<A, E, R>, layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined) => Stream<A, E | EL, Exclude<R, AL> | RL>) (+1 overload)
Creates a function that can be called in data-first style or data-last
(pipe-friendly) style.
When to use
Use to expose one implementation through both direct and pipe-friendly
call styles.
Details
Pass either the arity of the uncurried function or a predicate that decides
whether the current call is data-first. Arity is the common case. Use a
predicate when optional arguments make arity ambiguous.
Example (Selecting data-first or data-last style by arity)
import { Function, pipe } from "effect"
const sum = Function.dual<
(that: number) => (self: number) => number,
(self: number, that: number) => number
>(2, (self, that) => self + that)
console.log(sum(2, 3)) // 5
console.log(pipe(2, sum(3))) // 5
Example (Defining overloads with call signatures)
import { Function, pipe } from "effect"
const sum: {
(that: number): (self: number) => number
(self: number, that: number): number
} = Function.dual(2, (self: number, that: number): number => self + that)
console.log(sum(2, 3)) // 5
console.log(pipe(2, sum(3))) // 5
Example (Selecting data-first or data-last style with a predicate)
import { Function, pipe } from "effect"
const sum = Function.dual<
(that: number) => (self: number) => number,
(self: number, that: number) => number
>(
(args) => args.length === 2,
(self, that) => self + that
)
console.log(sum(2, 3)) // 5
console.log(pipe(2, sum(3))) // 5
dual((args: IArgumentsargs) => const isStream: (
u: unknown
) => u is Stream<unknown, unknown, unknown>
Checks whether a value is a Stream.
Example (Checking whether a value is a Stream)
import { Console, Effect, Stream } from "effect"
const program = Effect.gen(function*() {
const stream = Stream.make(1, 2, 3)
const notStream = { data: [1, 2, 3] }
yield* Console.log(Stream.isStream(stream))
// true
yield* Console.log(Stream.isStream(notStream))
// false
})
Effect.runPromise(program)
isStream(args: IArgumentsargs[0]), <function (type parameter) A in <A, E, R, AL, EL = never, RL = never>(self: Stream<A, E, R>, layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): Stream<A, E | EL, Exclude<R, AL> | RL>
function (type parameter) E in <A, E, R, AL, EL = never, RL = never>(self: Stream<A, E, R>, layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): Stream<A, E | EL, Exclude<R, AL> | RL>
function (type parameter) R in <A, E, R, AL, EL = never, RL = never>(self: Stream<A, E, R>, layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): Stream<A, E | EL, Exclude<R, AL> | RL>
function (type parameter) AL in <A, E, R, AL, EL = never, RL = never>(self: Stream<A, E, R>, layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): Stream<A, E | EL, Exclude<R, AL> | RL>
function (type parameter) EL in <A, E, R, AL, EL = never, RL = never>(self: Stream<A, E, R>, layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): Stream<A, E | EL, Exclude<R, AL> | RL>
function (type parameter) RL in <A, E, R, AL, EL = never, RL = never>(self: Stream<A, E, R>, layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): Stream<A, E | EL, Exclude<R, AL> | RL>
self: Stream<A, E, R>(parameter) self: {
channel: Channel.Channel<Arr.NonEmptyReadonlyArray<A>, E, void, unknown, unknown, unknown, R>;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
}
interface Stream<out A, out E = never, out R = never>A Stream<A, E, R> describes a program that can emit many A values, fail
with E, and require R.
Details
Streams are pull-based with backpressure and emit chunks to amortize effect
evaluation. They support monadic composition and error handling similar to
Effect, adapted for multiple values.
Example (Creating and consuming streams)
import { Console, Effect, Stream } from "effect"
const program = Effect.gen(function*() {
yield* Stream.make(1, 2, 3).pipe(
Stream.map((n) => n * 2),
Stream.runForEach((n) => Console.log(n))
)
})
Effect.runPromise(program)
// Output:
// 2
// 4
// 6
Stream<function (type parameter) A in <A, E, R, AL, EL = never, RL = never>(self: Stream<A, E, R>, layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): Stream<A, E | EL, Exclude<R, AL> | RL>
function (type parameter) E in <A, E, R, AL, EL = never, RL = never>(self: Stream<A, E, R>, layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): Stream<A, E | EL, Exclude<R, AL> | RL>
function (type parameter) R in <A, E, R, AL, EL = never, RL = never>(self: Stream<A, E, R>, layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): Stream<A, E | EL, Exclude<R, AL> | RL>
layer: | Layer.Layer<AL, EL, RL>
| Context.Context<AL>
import LayerLayer.interface Layer<in ROut, out E = never, out RIn = never>A Layer describes how to build one or more services for dependency injection.
When to use
Use to model construction of application services for dependency injection,
especially when services have dependencies, can fail during construction, or
need scoped setup and release.
Details
A Layer<ROut, E, RIn> represents ROut as the services this layer
provides, E as the possible errors during layer construction, and RIn as
the services this layer requires as dependencies.
Layer<function (type parameter) AL in <A, E, R, AL, EL = never, RL = never>(self: Stream<A, E, R>, layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): Stream<A, E | EL, Exclude<R, AL> | RL>
function (type parameter) EL in <A, E, R, AL, EL = never, RL = never>(self: Stream<A, E, R>, layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): Stream<A, E | EL, Exclude<R, AL> | RL>
function (type parameter) RL in <A, E, R, AL, EL = never, RL = never>(self: Stream<A, E, R>, layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): Stream<A, E | EL, Exclude<R, AL> | RL>
import ContextContext.interface Context<in Services>Immutable collection of service implementations used for dependency
injection in Effect programs.
Details
The type parameter tracks the service identifiers available in the context.
At runtime, services are stored by each key's string key.
Example (Creating a context with multiple services)
import { Context } from "effect"
// Create a context with multiple services
const Logger = Context.Service<{ log: (msg: string) => void }>("Logger")
const Database = Context.Service<{ query: (sql: string) => string }>(
"Database"
)
const context = Context.make(Logger, {
log: (msg: string) => console.log(msg)
})
.pipe(Context.add(Database, { query: (sql) => `Result: ${sql}` }))
Context<function (type parameter) AL in <A, E, R, AL, EL = never, RL = never>(self: Stream<A, E, R>, layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): Stream<A, E | EL, Exclude<R, AL> | RL>
options: | {
readonly local?: boolean | undefined
}
| undefined
local?: boolean | undefinedlocal?: boolean | undefined
} | undefined
): interface Stream<out A, out E = never, out R = never>A Stream<A, E, R> describes a program that can emit many A values, fail
with E, and require R.
Details
Streams are pull-based with backpressure and emit chunks to amortize effect
evaluation. They support monadic composition and error handling similar to
Effect, adapted for multiple values.
Example (Creating and consuming streams)
import { Console, Effect, Stream } from "effect"
const program = Effect.gen(function*() {
yield* Stream.make(1, 2, 3).pipe(
Stream.map((n) => n * 2),
Stream.runForEach((n) => Console.log(n))
)
})
Effect.runPromise(program)
// Output:
// 2
// 4
// 6
Stream<function (type parameter) A in <A, E, R, AL, EL = never, RL = never>(self: Stream<A, E, R>, layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): Stream<A, E | EL, Exclude<R, AL> | RL>
function (type parameter) E in <A, E, R, AL, EL = never, RL = never>(self: Stream<A, E, R>, layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): Stream<A, E | EL, Exclude<R, AL> | RL>
function (type parameter) EL in <A, E, R, AL, EL = never, RL = never>(self: Stream<A, E, R>, layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): Stream<A, E | EL, Exclude<R, AL> | RL>
type Exclude<T, U> = T extends U
? never
: T
Exclude from T those types that are assignable to U
Exclude<function (type parameter) R in <A, E, R, AL, EL = never, RL = never>(self: Stream<A, E, R>, layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): Stream<A, E | EL, Exclude<R, AL> | RL>
function (type parameter) AL in <A, E, R, AL, EL = never, RL = never>(self: Stream<A, E, R>, layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): Stream<A, E | EL, Exclude<R, AL> | RL>
function (type parameter) RL in <A, E, R, AL, EL = never, RL = never>(self: Stream<A, E, R>, layer: Layer.Layer<AL, EL, RL> | Context.Context<AL>, options?: {
readonly local?: boolean | undefined;
} | undefined): Stream<A, E | EL, Exclude<R, AL> | RL>
const fromChannel: <
Arr extends Arr.NonEmptyReadonlyArray<any>,
E,
R
>(
channel: Channel.Channel<
Arr,
E,
void,
unknown,
unknown,
unknown,
R
>
) => Stream<
Arr extends Arr.NonEmptyReadonlyArray<infer A>
? A
: never,
E,
R
>
Creates a stream from a array-emitting Channel.
Example (Creating a stream from an array-emitting channel)
import { Channel, Console, Effect, Stream } from "effect"
const program = Effect.gen(function*() {
const channel = Channel.succeed([1, 2, 3] as const)
const stream = Stream.fromChannel(channel)
const result = yield* Stream.runCollect(stream)
yield* Console.log(result)
})
// Output: [ 1, 2, 3 ]
fromChannel(import ChannelChannel.const provide: {
<A, E = never, R = never>(
layer:
| Layer.Layer<A, E, R>
| Context.Context<A>,
options?:
| { readonly local?: boolean | undefined }
| undefined
): <
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>(
self: Channel<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>
) => Channel<
OutElem,
OutErr | E,
OutDone,
InElem,
InErr,
InDone,
Exclude<Env, A> | R
>
<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env,
A,
E = never,
R = never
>(
self: Channel<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>,
layer:
| Layer.Layer<A, E, R>
| Context.Context<A>,
options?:
| { readonly local?: boolean | undefined }
| undefined
): Channel<
OutElem,
OutErr | E,
OutDone,
InElem,
InErr,
InDone,
Exclude<Env, A> | R
>
}
self: Stream<A, E, R>(parameter) self: {
channel: Channel.Channel<Arr.NonEmptyReadonlyArray<A>, E, void, unknown, unknown, unknown, R>;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
}
Stream<A, E, R>.channel: Channel.Channel<Arr.NonEmptyReadonlyArray<A>, E, void, unknown, unknown, unknown, R>(property) Stream<A, E, R>.channel: {
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
}
layer: | Layer.Layer<AL, EL, RL>
| Context.Context<AL>
options: | {
readonly local?: boolean | undefined
}
| undefined
Referenced by 1 symbols